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Category: history of cryptography

  • AI Used to Decrypt Medieval Ciphers

    AI Used to Decrypt Medieval Ciphers Researchers are using machine learning algorithms to decrypt historical pencil-and-paper ciphers. Bruce Schneier Go to bruce schneier

  • Medieval Encrypted Letter Decoded

    Medieval Encrypted Letter Decoded Sent by a Spanish diplomat. Apparently people have been working on it since it was rediscovered in 1860. Bruce Schneier Go to bruce schneier

  • Inventors of Quantum Cryptography Win Turing Award

    Inventors of Quantum Cryptography Win Turing Award Charles Bennett and Gilles Brassard have won the 2026 Turing Award for inventing quantum cryptography. I am incredibly pleased to see them get this recognition. I have always thought the technology to be fantastic, even though I think it’s largely unnecessary. I wrote up my thoughts back in…

  • Substitution Cipher Based on The Voynich Manuscript

    Substitution Cipher Based on The Voynich Manuscript Here’s a fun paper: “The Naibbe cipher: a substitution cipher that encrypts Latin and Italian as Voynich Manuscript-like ciphertext“: Abstract: In this article, I investigate the hypothesis that the Voynich Manuscript (MS 408, Yale University Beinecke Library) is compatible with being a ciphertext by attempting to develop a…

  • Book Review: The Business of Secrets

    Book Review: The Business of Secrets The Business of Secrets: Adventures in Selling Encryption Around the World by Fred Kinch (May 24, 2004) From the vantage point of today, it’s surreal reading about the commercial cryptography business in the 1970s. Nobody knew anything. The manufacturers didn’t know whether the cryptography they sold was any good.…

  • 1965 Cryptanalysis Training Workbook Released by the NSA

    1965 Cryptanalysis Training Workbook Released by the NSA In the early 1960s, National Security Agency cryptanalyst and cryptanalysis instructor Lambros D. Callimahos coined the term “Stethoscope” to describe a diagnostic computer program used to unravel the internal structure of pre-computer ciphertexts. The term appears in the newly declassified September 1965 document Cryptanalytic Diagnosis with the…

  • Jim Sanborn Is Auctioning Off the Solution to Part Four of the Kryptos Sculpture

    Jim Sanborn Is Auctioning Off the Solution to Part Four of the Kryptos Sculpture Well, this is interesting: The auction, which will include other items related to cryptology, will be held Nov. 20. RR Auction, the company arranging the sale, estimates a winning bid between $300,000 and $500,000. Along with the original handwritten plain text…

  • SIGINT During World War II

    SIGINT During World War II The NSA and GCHQ have jointly published a history of World War II SIGINT: “Secret Messengers: Disseminating SIGINT in the Second World War.” This is the story of the British SLUs (Special Liaison Units) and the American SSOs (Special Security Officers). Bruce Schneier Go to bruce schneier

  • The Combined Cipher Machine

    The Combined Cipher Machine Interesting article—with photos!—of the US/UK “Combined Cipher Machine” from WWII. Bruce Schneier Go to bruce schneier